Some Remarks on New Trends in Using Waste Aggregates in Civil Engineering: An Overview

The extensive development of construction, in which cement concrete remains the key composite, enforces the need for particular environmental concerns. This applies to aspects, including ecological challenges in the cement industry and the rational use of natural construction aggregates. This review article focuses on new trends in the use of waste aggregate, with particular emphasis on concrete recycled aggregate and waste sands. The state of the art was analysed, including many years of own studies on modification of properties of waste aggregate and concrete composites made from it. It was assessed that among possible ways of quality improvement of RCA, the most promising for the macro scale seems to be carbonation, unlike biodeposition. The latter, novel and undoubtedly interesting from a scientific viewpoint, has not been studied sufficiently, and the real obstacle is the cost of its implementation in practice. Multi-recycling, the pioneering proposal of recycled concrete aggregate management, can be viewed only in the ecological context for the moment. The use of waste sands from hydroclassification combined with steel fibres is the closest to implementation for constructional purposes in engineering practice.